1. Field of the Invention
This invention relates to an optical lens, optical lens unit, stacked type optical lens, optical system, and semiconductor laser apparatus which act on each of the rays of light emitted from a light-emitting unit which is a plurality of light-emitting devices arranged in an array, and in particular, relates to an optical lens, optical lens unit, stacked type optical lens, optical system, and semiconductor laser apparatus which collimates and condenses each ray of light.
2. Related Background of the Invention
An optical lens collimates (parallelizes) rays emitted from a semiconductor laser device as a light-emitting device, and the light is focused onto a minute spot at the light-receiving portion of an optical fiber or the like. The semiconductor laser device often takes the form of a semiconductor laser array, in which a plurality of light-emitting portions are arranged in a row; in this case, the optical lens also takes the form of an array which collimates each of the rays of light from each of the light-emitting portions. Japanese Patent Laid-open No. H7-98402 discloses an optical path converter in which a plurality of cylindrical lenses are arranged in parallel. International Unexamined Patent No. WO99/57791 and European Unexamined Patent No. EP1006382A1 disclose an optical lens for semiconductor lasers in which a plurality of cylindrical lenses are formed integrally. These optical path converters and cylindrical lenses for optical lenses each collimate rays of light emitted from each of the light-emitting portions of a semiconductor laser array.
As a result of studies of the above conventional type optical lenses, the inventor of this invention discovered that the above conventional optical lenses have the following problems.
(1) Using the optical path converter disclosed in Japanese Patent Laid-open No. H7-98402, it is extremely difficult to arrange each of the cylindrical lenses to collimate incident rays one-to-one with the light-emitting portions of semiconductor laser devices.
(2) In the optical lenses disclosed in International Unexamined Patent No. WO99/57791 and European Unexamined Patent No. EP1006382A1, cylindrical lenses are formed integrally, so that problems such as in (1) do not occur; but there is the problem that, because the depressions and protrusions of each cylindrical lens are exposed to the outside, dirt tends to accumulate in such places, and this blocks light and affects the light emission performance.
An object of this invention is to provide an optical lens, optical lens unit, stacked type optical lens, optical system, which promote a simple arrangement to a position enabling action on each ray of light emitted from each of a plurality of light-emitting portions of a light-emitting device, the light-emitting portions of which are arranged in an array, and which can adequately prevent adverse effects on the light emission performance, and semiconductor laser apparatus.
In order to attain the above object, the optical lens of this invention is an optical lens which, after acting on each of the rays of light emitted from a light-emitting device the plurality of light-emitting portions of which are arranged in an array, emits the rays of light, and which comprises:
one or a plurality of first optical member arrays, each having a plurality of columnar optical members comprising a first optical action portion, which has a curved surface on either the light incidence side or on the light emission side and which acts on each ray of light emitted from each light-emitting portion in the x-axis direction, and in which each columnar optical member is arranged on the same plane; and,
a second optical member, formed in a columnar shape from a transparent material, in the interior of which are embedded in parallel one or two first optical member arrays, along the column axis direction; and, in which
the constituent material of each columnar optical member has a refractive index differing from that of the transparent material of the second optical member.
In such an optical lens, because the first optical member array acting on incident light from the light-emitting device is embedded in the second optical member in an integral structure, arrangement in a position to enable action on each of the incident rays of light can be easily performed.
Moreover, because the depressions and protrusions due to the convex curved surfaces of each columnar optical member, formed by arrangement in an array of each columnar optical member, are covered by the second optical member and are not exposed to the outside, there is no accumulation of dirt on these portions.
Further, the first optical member array is reinforced by the second optical member, and so has excellent strength.
In this specification, xe2x80x9cacts on a ray of lightxe2x80x9d means that the angle of divergence of an incident divergent ray of light is reduced before the ray of light exits.
It is desirable that the columnar optical members be in mutual contact in the array arrangement. In this case, the array pitch of the columnar optical members is shorter than in the case in which the plurality of columnar optical members are mutually separated in the array, so that the lens can easily be applied to a semiconductor laser array which is a light-emitting device in which the array pitch of the light-emitting portions is short. Also, each of the first optical action portions of the columnar optical member acts precisely in the X-axis direction on the ray of light emitted from each light-emitting portion.
Each of the columnar optical members has a pair of contact plane surfaces, formed on the side faces and mutually parallel; it is further desirable that the first optical member array be formed with each of the columnar optical members arranged in the array in mutual contact at the contact plane surfaces. By this means, it is easy to form the first optical member array, and the optical lens becomes inexpensive.
Each of the columnar optical members may be formed integrally. When the columnar optical members are formed integrally, the operation of arrangement of the individual columnar optical members becomes unnecessary, and the optical lens can be manufactured efficiently, and the lens so becomes inexpensive.
It is desirable that the second optical member have a curved surface which acts on either incident light or exiting light. The optical lens comprises two optical members capable of acting on light, so that it is possible to manufacture the optical lens where the refractive indices of the two optical members are set appropriately, and in particular so that the refractive index difference is made large. xe2x80x9cX-axis directionxe2x80x9d means the direction of arrangement of each light-emitting portion in the light-emitting device when the direction of arrangement of the plurality of columnar optical members and the direction of arrangement of the plurality of light-emitting portions are parallel; that is, xe2x80x9cX-axis directionxe2x80x9d means the direction of arrangement of the plurality of columnar optical members.
For example, the curved surface of the second optical action portion may be formed at the exit face of the second optical member, to act in the X-axis direction on each ray of light emitted from each light-emitting portion. By this means, it is possible to condense each of the rays emitted from the first optical member array.
As the curved surface of the second optical action portion, either the incident surface or the exit surface of the second optical member is formed into a curved surface, to act in the Y-axis direction on each ray of light emitted from each light-emitting portion. By this means, emitted light is obtained which has been acted on in both directions by the optical lens, in addition to the action in the X-axis direction by the first optical action portion of the columnar optical member. Here, xe2x80x9cY-axis directionxe2x80x9d signifies the direction perpendicular to the X-axis direction and to the optical axis.
It is desirable that the thermal expansion coefficient of the constituent material of the columnar optical members be higher than that of the transparent material of the second optical member. If the optical lens is manufactured with a material of high thermal expansion coefficient covered by a material with a low thermal expansion coefficient, a crimping effect results in a durable structure which resists cracking.
It is desirable that the constituent material of columnar optical members have a yield point which is higher than that of the transparent material of the second optical member. The difference in yield points can be utilized to manufacture an embedded type optical lens using a drawing process.
The optical lens unit of this invention comprises the above optical lens, and a juxtaposed optical lens, placed adjacent to the above optical lens, and comprising a third optical action portion which acts in the Y-axis direction on each ray of light emitted from each light-emitting portions. Because the juxtaposed optical lens comprising the third optical action portion is provided separately, it can be placed in a desired position.
In the optical lens unit of this invention, the above optical lenses, each comprising a first optical member array, are arranged into an array of two parallel rows. In such an optical lens unit, the two optical lenses are arranged into two rows, and so it is possible to adjust the distance between the optical action portions in each of the optical lenses.
It is desirable that the second optical member of one of the two rows of optical lenses arranged in parallel is formed with a curved surface at either the light incidence face or the light exiting face of the second optical members, to comprise a second optical action portion which acts in the Y-axis direction on each ray of light emitted from each light-emitting portion.
The first optical member array of the optical lens arranged on the exit side of the two rows of optical lenses arranged in parallel, has a plurality of columnar optical members comprising first optical action portions, with curved surfaces formed on the light incidence side and on the light emission side, and which act on each ray of light emitted from each light-emitting portion. The first optical member array of the optical lens arranged on the incidence side of the two rows of optical lenses arranged in parallel may have a plurality of columnar optical members comprising first optical action portions, with a curved surface formed on the light incidence side, and which act on each ray of light emitted from each light-emitting portion. By means of the optical lens arranged on the incidence side, it is possible to act on light incident from light-emitting devices according to the divergence angle of the light incident from each light-emitting portion and the pitch of the columnar optical members, and to adjust the emitted light.
An optical lens unit of this invention further comprises a juxtaposed optical lens, juxtaposed to two rows of optical lenses arranged in parallel, and comprising a third optical action portion, which acts in the Y-axis direction on each ray of light emitted from each light-emitting portion. Because the juxtaposed optical lens comprising the third optical action portion is provided separately, the juxtaposed optical lens can be placed in a prescribed position.
An optical system of this invention comprises a light-emitting device in which a plurality of light-emitting portions are arranged in an array; the above optical lens, which acts on each ray of light emitted from the light-emitting device; and a light-receiving device, in which one or a plurality of light-receiving portions which receive light emitted from the optical lens are arranged in an array.
In this optical system, when rays of light emitted from the plurality of light-emitting portions of the light-emitting device are incident on the optical lens, the first optical action portions of the plurality of columnar optical members in the optical lens act on the incident light in the X-axis direction. Consequently the divergence angle and the like of the emitted light can be adjusted. Hence even in cases when the light-receiving portion of the light-receiving device is extremely small, or when the array pitch of light-receiving portions is extremely small, each ray of light emitted from individual light-emitting portions can be reliably guided to the respective light-receiving portions. Also, because the plurality of columnar optical members of the first optical member array are constrained by the second optical member, when the optical lens is placed relative to a light-emitting device in which a plurality of light-emitting portions are placed in an array, it is possible to position the optical lens more simply than when columnar optical members are positioned independently for each light-emitting portion, so that simple installation of the optical system is possible. Also, when a plurality of columnar optical members are placed in an array, protruding or depressed portions are formed due to the first optical action portions of the plurality of columnar optical members, because curved surfaces are formed in the first optical action portions; in the above optical lens, these protruding or depressed portions are covered by the second optical member and are not exposed to the outside, so that dirt and the like does not accumulate on these portions. Hence excellent light emission performance can be maintained over extended periods of time, without exchanging, cleaning, or the like of the optical lens. Moreover, because the optical lens is excellent in strength, the frequency with which the optical lens is-replaced in an optical system is sufficiently reduced.
Also, an optical lens of this invention comprises:
one or a plurality of first optical member arrays, having a plurality of columnar optical members arranged in an array along the X-axis direction, which have curved surfaces formed in each of the above plurality of columnar optical members, and which have a first optical action portion which acts in the above X-axis direction on light rays incident on the above columnar optical members; and,
a second optical member, which constraines the above plurality of columnar optical members of the above first optical member arrays, which covers the above first optical action portions of the above plurality of columnar optical members, and which is formed from a transparent material; and wherein
the refractive indices of the constituent material of the above columnar optical members and of the above transparent material of the above second optical member are different.
In this optical lens, the plurality of columnar optical members of the first optical member array are constrained in place by the second optical member. Consequently when the optical lens is positioned with respect to a light-emitting device in which are placed a plurality of light-emitting portions in an array, the operation of placing the optical lens can be performed extremely easily compared with the case in which columnar optical members are placed independently for each light-emitting portion. Further, when the optical lens is placed opposing the above light-emitting device, if the light rays emitted from each of the light-emitting portions of the light-emitting device are incident on columnar optical members of the optical lens, the first optical action portions of the columnar optical members act in the X-axis direction on the light incident on the columnar optical members. Also, when a plurality of columnar optical members are positioned, because the first optical action portion forms a curved surface, protrusions and depressions are formed by the first optical action portions of the plurality of columnar optical members, but these protrusions and depressions are covered by the second optical member and are not exposed outside, so that dirt and the like does not accumulate in these portions. Further, the first optical member array is constrained and reinforced by the second optical member, so that the strength of the optical lens is superior to that in cases where the first optical member array is not constrained by a second optical member.
An optical lens unit of this invention comprises the above optical lens, and a juxtaposed optical lens, which is placed juxtaposed with the above optical lens, and which comprises a third optical action portion which acts in the Y-axis direction on incident rays of light.
In this optical lens unit, the first optical action portions of columnar optical members in the above optical lens act in the X-axis direction, and the third optical action portion of the juxtaposed optical lens acts in the Y-axis direction. Hence by means of this optical lens unit, incident light rays can be acted on in both the X-axis and the Y-axis directions. Furthermore, the juxtaposed optical lens is provided separately from the columnar optical members, so that the distance between the first optical action portions and the third optical action portion can be adjusted as appropriate to the purpose.
An optical lens unit of this invention may have a first optical lens and second optical lens placed to be mutually parallel, in which the above first optical lens and the above second optical lens are each the above-described optical lens, which comprises the above-described first optical member array. In such an optical lens unit, because two optical lenses are placed in a parallel array, the distance between the respective optical action portions can be adjusted.
A stacked type optical lens of this invention is a stacked type optical lens which, after acting on each of the rays of light emitted from a light-emitting device in which a plurality of light-emitting portions are arranged in an array, emits the rays of light, and has the form of a stack of a plurality of levels of the above optical lenses.
According to such a stack type optical lens, the first optical member array acting on incident light from the light-emitting device is embedded in the second optical member in an integral structure, so that placement in a position enabling action on each incident light ray can be performed simply. Further, by placing columnar optical members in an array, the protruding and depressed portions due to the curved surfaces of the columnar optical members are covered by the second optical member and are not exposed to the outside, so that dirt and the like does not accumulate on these portions. Moreover, because the first optical member array is reinforced by the second optical member, the optical lens is excellent in strength. And, because the optical lens has a form in which a plurality of levels are stacked, the optical lens is adaptable to a light-emitting device in which light-emitting portions are stacked in a plurality of levels.
It is preferable that the second optical member in each level have a second optical action portion which forms a curved surface on the ray incidence face of the second optical member, and acts in the Y-axis direction on each incident light ray; and that the second optical member further comprise a condensing portion in which curved surfaces are formed in the entirety of the light emission face of the second optical member in each level, and which acts on each emitted light ray in both the Y-axis direction and in the X-axis direction, and condenses light in one place.
By this means, each of the emitted light rays from the light-emitting devices stacked in a plurality of levels can all be condensed in one place by the condensing portion.
Moreover, an optical system of this invention comprises a light-emitting device in which a plurality of light-emitting portions are arranged in an array; the above-described stack type optical lens, which acts on each of the rays of light emitted from the light-emitting device; and a light-receiving device, in which one or a plurality of light-receiving portions which receive rays of light emitted by the stack type optical lens are arranged in an array.
Thus, an optical system is provided comprising a stack type optical lens which can easily be positioned with respect to a light-emitting device in which, for example, a plurality of semiconductor laser arrays, each of which has light-emitting portions arranged in a row, are stacked in a plurality of levels, and which is excellent in light emission performance without accumulation of dirt or the like.
Also, a stacked type optical lens of this invention comprises:
one or a plurality of first optical member arrays, each having a plurality of columnar optical members arranged in an array along the X-axis direction, each of which has a curved surface, and has a first optical action portion which acts in the above X-axis direction on rays of light incident on the above columnar optical members; and,
a second optical member, having a third and a fourth face formed on both sides of the first optical member arrays, in which at least one of the above third and fourth faces has a plurality of curved surfaces having second optical action portions which act on incident light rays in the Y-axis direction, and which is formed from a transparent material.
In such a stacked type optical lens also, the first optical member arrays which act on incident light rays from a light-emitting device are embedded in the second optical member in an integral structure, so that placement in a position enabling action on each of the incident light rays can be easily performed. And the protruding and depressed portions due to the curved surfaces of columnar optical members, formed through placement in an array of the columnar optical members, are covered by the second optical member and not exposed to the outside, so that there is no accumulation of dirt or the like on these portions. Also, because the first optical member arrays are reinforced by the second optical member, the stacked type optical lens is excellent in strength. And because the stacked type optical lens has a form in which the optical lens are stacked in a plurality of levels, it is adaptable to a light-emitting device in which semiconductor laser arrays, in which a plurality of light-emitting portions are arranged in a row, are stacked in a plurality of levels.
Also, an optical lens of this invention comprises:
a first optical member array, having a plurality of columnar optical members formed in a columnar shape from a transparent material, to include, in the external face on at least one side, a first optical action portion consisting of a curved surface parallel to a first axis, and in which the above plurality of columnar optical members are placed in an array shape such that the above plurality of first axes are mutually parallel in a prescribed plane; and,
a second optical member, formed in a columnar shape from a transparent material having an index of refraction different from that of the above columnar optical members, to include, in the external face on at least one side, a second optical action portion consisting of a curved surface parallel to a second axis, and with at least the above first optical action portions of the above first optical member array embedded therein, such that the above second axis is perpendicular to the above plurality of first axes; and in which
the first and second optical action portions act on light on optical axes which intersect orthogonally in a prescribed plane.
According to the optical lens of this invention, the first optical member array, which acts on incident light rays from a light-emitting device, is embedded in the second optical member in an integral structure, so that placement in a position enabling action on each of the incident light rays can be easily performed. Also, because the protruding and depressed portions due to the curved surfaces of each of the columnar optical members, formed by arrangement in an array of columnar optical members, are covered by the second optical member and not exposed to the outside, there is no accumulation of dirt or the like on these portions. And, because the first optical member array is reinforced by the second optical member, the optical lens is excellent in strength.
An optical lens with simple structure can easily be manufactured using known methods in minute sizes. Consequently manufacturing can be performed with the size of the second optical member, and the sizes and number of the columnar optical members in the first optical member array, easily adjusted according to the conditions of placement of a plurality of light sources arranged in an array, or the conditions of placement of a plurality of illumination spots arranged in an array. Hence it is possible to make the first optical action portions of a plurality of columnar optical members in the first optical member array correspond to each minute light source; and, the optical lens can easily be placed in a minute range before the onset of overlapping of light rays emitted from adjacent minute light sources, so that incident light rays from light sources can be acted on independently for each light source. Further, even when the plurality of minute light sources have astigmatism and are arranged in an array, because in an optical lens of this invention the second optical action portion of the second optical member and the plurality of first optical action portions in the first optical member array are arranged as described above, so that the vertical components and parallel components of beams emitted from the light sources, with different divergent angles, can be acted on together.
Also, the first optical action portions of the plurality of columnar optical members constituting the first optical member array can correspond to a plurality of illumination spots arranged in an array one-to-one, and the plurality of emitted light rays which have been subjected to action can be illuminated together, a plurality of prescribed corresponding illumination spots.
Here the xe2x80x9cfirst axisxe2x80x9d is the axis (central axis) passing through the geometrical centers of the two base faces of the columnar optical members, and refers to the axial line which is parallel with the extending direction of the columnar optical members. The xe2x80x9csecond axisxe2x80x9d is the axis (central axis) passing through the geometrical centers of the two base faces of the columnar second optical member, and refers to the direction of arrangement of the columnar optical member (the axial line parallel with the extending direction of the second optical member).
It is preferable that the transparent material of the above columnar optical members have a thermal expansion coefficient higher than that of the transparent material of the second optical member. If the optical lens is manufactured with a material having a high thermal expansion coefficient covered by a material with a low coefficient, a crimping effect results in a durable structure which resists cracking.
It is preferable that the transparent material of the above columnar optical members have a yield point higher than that of the transparent material of the above second optical member. The difference in yield points can be utilized to manufacture an embedded type optical lens using a drawing process.
The above columnar optical members may, for example, be formed into cylindrical shapes.
The above columnar optical members may be formed into semi-cylindrical shapes, with the outer face of the side opposite the above curved surface be formed into a planar surface.
It is preferable that the above columnar optical members be formed with a pair of planar side faces between the above curved surface, and the outer face opposite the above curved surface, and that the above first optical member array be formed by arranging in an array the above columnar optical members, so as to be in mutual contact at the above planar side faces. Because planar side faces are formed, the plurality of columnar optical members can be easily arranged in an array, and the optical lens can be manufactured efficiently. As a result, the optical lens becomes inexpensive.
The above second optical member may be formed into, for example, a cylindrical shape.
The above second optical member may be formed into, for example, a semispherical shape, with the outer face opposing the curved surface formed into a planar face.
The above optical lens may further have a pair of rolling prevention means, provided on both ends of the second optical member, which prevents rolling of the above second optical member. Through these rolling prevention means, rolling of the second optical member is prevented, so that when mounting the second optical member on a semiconductor laser array in which a plurality of light-emitting portions are placed in an array, the mounting operation is extremely easy. Also, the angle of mounting of the optical lens on the semiconductor laser array is determined.
It is preferable that the above pair of rolling prevention means have contact faces consisting of planar faces respectively.
In this case, because the contact face is a plane, when the rolling prevention means of adjacent optical lenses are brought into mutual contact at the contact faces, it is possible to easily stack a plurality of optical lenses, so that, for example, the operation of mounting on a light-emitting device in which semiconductor laser arrays are stacked in a plurality of levels becomes easy.
A semiconductor laser apparatus of this invention has a semiconductor laser array, in which a plurality of light-emitting portions are arranged in an array; ray parallelizing means, which parallelizes and emits light rays emitted from the above plurality of light-emitting portions; and a condensing optical system, which condenses and outputs the rays emitted by the above ray parallelizing means; the above ray parallelizing means is the above optical lens, and the direction of the array of the above plurality of light-emitting portions in the above semiconductor laser array is parallel to the direction of the array of the above plurality of columnar optical members in the above optical lens.
In this semiconductor laser apparatus, the number of columnar optical members in the first optical member array is matched with the number of light-emitting portions of the semiconductor laser array used; in addition, when the pitch of the plurality of columnar optical members is made equal to the pitch of the array of light-emitting portions used, the second optical member acts in the Y-axis direction on the laser beams emitted from the respective plurality. of light-emitting portions, and the columnar optical members act in the X-axis direction on the laser beams emitted from the respective plurality of light-emitting portions.
It is preferable that the two end faces of the above columnar optical members be exposed from the second optical member. If the two end faces are thus exposed from the second optical member, when the optical lens is being placed with respect to a semiconductor laser array, positioning of the first optical action portions with respect to the light-emitting portions becomes easy, and the region up to the interface of the second optical member can be regarded as the first optical action portions.